Stoker, including gas feedback prevention means



Dec. 26, 1950 P. c. MALMSTEN 2,535,939

sToKER, INCLUDING @As FEEDBACK PREVENTION MEANS A Filed May 4, 1946 A 2 Sheefcs-Sheet 1 Dec. 26, 1950 P. c. MALMsTEN 2,535,939

STOKER, INCLUDING GAS FEEDBACK PREVENTION MEANS Filed May 4, 1946 A2 Sheets-Sheet 2 1 Ven/or img; fn@

//orney Patented Dec. 26, 1950 Philip or rjpvmlmstenl'v Milwakee; Wiss; assrg fqj m frisirivlentienfrelates stekerlbnstrueun 1 f1 air det'afgaau the: fedgtmji and; has:` particular relatie@ to the construetien ,a andr assembly of the; shear" plate ofv th stok'er inooznhirlatonwith the1A air supply duct and feediscrew housihlgilu H @nef objectofth inyentionvisto proyitlej an air" supplyduct and-'feedfscreyvl housing construeinw tion that permitsy enpl'oymertof" a shear plate y l havingf passagesftherthrdu'ghfor passage offair fromfthe air duectand' intoi the feed" screw housing to overcome and* prevent smoke back.

Another objeet'fig tsfprov-ide aqno'ver airain,- l p1-,b expensive structurelfqr' eliminating smoke Hack o y hb fuel.' The;` :motor in' al StokerA whereinposityeforward air pressure y llehCiQ ruit". throughthe` fuel feed tube preventsfthe'. escape 'it off gas fandf smoke.

Another objectfis: to'i pr'ovlieV afpressure; chantber inf` avshear plate?" to." overcome smoke back Airl theifeed'l tulle;v t

H'fUrther object; istA providefan-i air: supply duetfandrfeedserew housingffconstructicnfwhich d x ",4A et j is compact permitting installation`= in; cramped tudialwlds-8-whichextend" stilistarlt'ially"V the quartersfandajvsubstantially-shorter?air'duetland length of bhemairyduct and tube and salthe feedscrew jbhts"therebetw`fni y t namwnessf-offthefpyramidedrtubeiandenes. aba ,l :frrriealrcbrrrmement ry; t tape s" essere 10W Harlem.

'.lhese:Av andi other' obiectsfof the inventioni will whi amoear` herenaf-tern connection r'With-the followheath ope ngvdescrption'yoff anrembodiment'of the inveni's` bacliQcl;` y x i tionesillustrated'in:the-accompanyingdrawings; 35 fleiShQldQrSy 'Son eachlslfeofpl If'fovrlap Fig;` .lrisarsideelevationy of!` the hopper and plate is olset from body Il and overlaps t'b 3`, retortassemblywithrthevretortfassemblybroken and the rear end I5 extends slightly" within l away* and:V sectionedeto showthe' feed` screw and lopperzi ernennt? Y y o Ther-wing nutsfls` are threaued'pnte trlestuas 2-isvaf` sectionftaken ora` line. 2-`2' of Fig: 1 I'fext'endngj Ada'goriallst' Wardly from' assenilly and looking toward the hopper with the shear plate''tosecure 'the Shear-plate inplaceg' pla'.te`-c`anlh'opper.L Walllfshown in elevation; ,Suitable pael-ing' mate'rallliis providedM be* Fig. 3 is a detail side elevation of the assembly tkwenthe fcrwardend I4oif"p1ate Wand tbel with the shearplate andi feedscrew removed and 4:, btWeena'nge'lZ and asseirlll- Yfplate 5"and` be- Fig. 5 isiaetapaplanview` oftha sheanlplate with vertical cross-section "and provided `Withlthe the passages therethroughshown in dotted lines; 5'@ longitudinal passage IS'Qtheretl'rihfWhieh ex;

Fig.- 6 is a longitudinal sectional View` partially tend's'fdownwardlylatthe, forward endandopens isa'zsecton taken onlinel-lxoillligil. from the 'real' end` pff' passage is? throng-inthe `'llhe drawings illstrate'alst'oker to W'hbhwthe shoulders 13 and' register with the aperturesfl inyentonhas been applied' andl'which, ngeneral, which extendfthrogh theftpof4 air duct' `Won comprises the retort I and the hopper Twhi'ch ealisdeoffthettibeopeningfill are connectedf-to'eachbtherbyfthe circular feed A portion oftheair forced airjrdct screw-` tube 3 and thelgenerally rectangularly Allows upwardlythrough'apertureszxl Qf erlieg'ar 3 and thence into feed screw tube 3. The shear plate thus provides a pressure chamber through which a positive forward air pressure is provided in feed tube 3 to prevent the backward flow of gas and smoke into the hopper 2.

Control of the flow of air through air duct 4 to retort l is obtained by the damper 22 which extends across the air duct and is adjustable to open automatically a predetermined amount when air is forced through the duct.

The air duct 4 is also provided with the cleanout opening 23 in one side thereof which is covered by the removable plate 24. A hose or other device may be inserted through opening 23 to remove ashes and foreign matter which may fall into the base of retort I. Plate 24 and opening 23 are located only slightly forwardly from shear plate I0 so that in a compact or angular assembly of the stoker with a furnace unit the plate can be readily removed and replaced.

Shear plate I0 is readily removed by the operator merely unthreading wing nuts l from studs I l and slipping the plate off from the studs.

Ordinarily a shear plate is provided in a Stoker for removal to gain access to the inside of the feed tube to take out foreign objects that have caused `the feed screw to cease operation due to the shearing of a pin or the like.

However, under the present invention shear plate I9 serves a dual purpose, since it not only :`l

operates as a shear plate but also to convey air from air duct 4 into feed tube 3 when blower 4 is 'in operation to provide a positive forward air pressure in the feed tube that will prevent backward flow of gas and smoke into the hopper and thenceout into the room in which the Stoker is located.

The invention provides a compact retort as sembly and a symmetrical design that is utilized to good advantage in providing a trap for gas and smoke without unsightly or expensive connections. The construction also improves the hopper capacity since the construction permits any extension of air duct 4 beneath the hopper to be located directly beneath the feed screw thus not requiring the hopper to be steeply pitched or otherwise designed to overcome location of an air duct extension to one side of thefeed screw.

Various embodiments of the invention may be employed within the scope of the accompanying claims.

I claim:

1. In a stoker, the combination of an air duct n; un

and a blower to force air forwardly through said duct, a feed screw housing nested longitudinally within said air duct, a coal feed screw disposed for rotation within said feed screw housing, and a shear plate removably provided at the entrance of the feed screw housing as a part of said housing and overlapping the top of said air duct for removal of foreign objects from the feed screw housing, said shear plate having a passage extending therethrough and being disposed in a forward direction and registering at one end with an aperture in said air duct and leading into the feed screw housing at the other end to by-pass air into the feed screw housing from the air duct and provide positive forward air pressure from the air duct within the feed screw housing and eliminate backward passage of gases and smoke through the housing when said blower is in operation and forcing air forwardly through said air duct.

2. In a Stoker, the combination of an air duct and a' blower yto force air forwardly through said 4 duct, a feed screw housing nested longitudinally within said air duct and welded te the top of the air duct to provide a closure for said air duct, said housing having an opening in the top at the entrance thereof, a vertical plate welded to the rear end of said air duct and feed screw housing, a shear plate removably bolted to said vertical plate and formed to close the opening in said feed screw housing and to overlap the same and the top of the .air duct, said shear plate being disposed for removal of foreign material from the feed screw housing, and a lpassage extending through said shear plate and being disposed in a forward direction and registering at one end with i an aperture in said air duct and extending to the inside of the feed screw housing at the other end to Dy-pass air into the feed screw housing from the air duct and provide positive forward air pressure within the feed screw housing during rotation of the feed screw and thereby eliminate backward passage of gases and smoke through the housing when said blower is in operation and forcing air forwardly through said air duct. y

3. In a stoker, the combination of a rectangular shaped air duct and a blower to force air forwardly therethrough, and a generally cylindrical feed screw housing extending longitudinally within the top wall of said duct, a hopper, anda shear plate provided as a part of the feed screw housing at the junction of the hopper andvhousing and disposed to overlap said air duct with a passage extending therethrough andregistering at one end with said air duct and at theother end with the inside of said feed screw housing to bypass air into the feed screw housing from the air duct and overcome backward iiow of gas and smoke therein when said blower is in operation and forcing air forwardly through said air duct.

4. In a stoker, thecombination of an air duct and a blower to force air forwardly through said duct, a feed screw housing nested within said air duct, a coal feed screw disposed for rotation within said housing, and a removable access plate assembled with said feed screw housing and disposed to overlap said air duct, said plate having a passage extending therethrough and being disposed in a forward direction and aligned at one end with an aperture in said air duct and leading into the feed screw housing at the other end to by-pass air into the feed screw housing from the air duct and to provide positive forward air pressure within the feed screw housing .for eliminating backward passage of gases and smoke through the housing when said blower is in operation and forcing air forwardly through said air duct.

PHILIP C. MALMSTEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 608,819 Wood Aug. 9, 1898 1,974,133 Carter Sept. 18, 1934 1,990,086 Nelson Feb. 5, 1935 2,051,282 Yerges Aug. 18, 1936 2,216,109 Castagna Oct. l, 19110 2,239,061 Sourber Alpr. 22, 1941 FOREIGN PATENTS y Number Country Date' 291.764 `Germany May 8, V1916 

